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Bathroom Sink improper drain

I saw season 9 opener where an AAV (air admittance valve) was used. I am wondering if that will solve my problem with my bathroom sink. The problem we are having is the sink is an under mount with no overflow / built in air channel. It just has the drain. Therefore when we use the sink it always backs up given an air bubble forms in the drain just under the plug. I was hoping adding an AAV will solve this problem by letting air into the pipe. I am not very familiar with plumbing so any help you can provide me will be greatly appreciated. Thank You.

Re: Bathroom Sink improper drain

For the AAV to work, you'd have to connect it to the drain line above (on the sink side) the J-bend / trap, and have the AAV above the height of the sink. Don't know how you'd accomplish that. Check with a good plumbing supply house for a new drain kit. Some manufacturers make better drains than others.

We had a similar problem where the strainer at the bottom of the bowl had holes in it. Those holes were the perfect size for bubbles to form and block the water from going down. We drilled the holes larger, and that solved the problem. Vent-less sinks can be very pretty to look at, but not very functional.

Re: Bathroom Sink improper drain

HoustonRemodeler, thank you for the information I think the easiest thing for me to do would be to just swab out the current sink with the exact same but with a vent built in. May not be the cheapest; however, I am not able to elevate the AAV about the sink given current configuration. Thanks again.

Re: Bathroom Sink improper drain

where's "nashua tech" when you need him. this doesn't make sense to me. for starters, any venting has to be tied in 6" above the highest water level achievable of any fixture on that floor. AAV's are not legal in some states like mass so you should check that out also. the fact that your sink doesn't have an over flow valve has nothing at all to do with how it drains. over flow valves are before the trap therefore they don't do anything in venting the fixture. i'd start with snaking the drain past the trap and make sure you have a clear pipe, if you don't call a plumber and save the hassle of exchanging your sink.

Re: Bathroom Sink improper drain

If there is no vent on the sink and you try to empty a sink full of water and there is on overflow on the sink it would be like holding your finger over a straw full of water. In this case if legal in his state a ATV would work. You are right a proper vent not an ATV must be tied in 6" above the flood rim of the fixture it is venting.